1. Technical Field
The invention is generally related to an adjustment plate for a grinder. More particularly, the present invention relates to an intermediate adjustment plate for adjustably retaining a fixture plate on a grinder table. Specifically, the present invention relates to an adjustment plate that secures a fixture plate to a grinder table while being adjustable about three axes.
2. Background Information
Lost wax casting is a common method for fabricating small parts that require specific tolerances. Lost wax casting is used to form a wide variety of parts including aircraft parts, plumbing fixtures, engine parts, and the like. The process involves first forming a model of the desired part. The wax model is then coated with a suitable material such as silicon or ceramic that forms a rigid shell about the wax part. Then, as the name implies, the wax is melted out of the shell and a mold is formed. Molten metal may then be poured into the mold and allowed to cool to form the desired part.
The opening in the mold into which the molten metal is poured results in an unwanted protuberance of metal on the cooled part. This undesirable protuberance is referred to as a "gate" in the art and must be removed for the molded part to meet specifications. One typical method of removing a gate is to first cut a large portion of the gate off with a saw, removing another portion of the material with a grinder, and then machining the part to final specifications. In order to properly machine a part, the grinding operation must yield a surface that meets machining specifications. As such, the grinding step of the process must be precisely performed to yield a usable part.
The known grinding process uses a large grinder such as an AW Bell grinder that is capable of quickly grinding the unwanted material away by using relatively large forces and high speeds. The speed of the process, however, entirely relies on a proper set up for the part. Currently a set-up man must secure an individual part on a grinding table such that the unwanted material will contact the grinding surface at the proper angle when the grinding table was moved into an operating position. To obtain the proper alignment of a part, the set-up person utilizes a fixture plate that includes a clamp to hold the part against the plate. Due to the relatively large forces created by the grinding process, the fixture plate also includes a plurality of back stops or side stops that help counteract the force of the grinding process. The back stops and side stops are typically welded to the fixture plate and arranged specifically for a given part such that the part to be ground fits snugly within these stops. The part is then clamped to the plate by a suitable clamp that is attached to the plate.
The set-up man then carefully aligns the plate with the belt and clamps the plate to the grinder table. The process of properly aligning the plate includes using shims to tilt the fixture plate about its various axes. This process is time consuming and must be repeated for each fixture prior to grinding. It is not uncommon for the set up process to consume up to one hour per fixture. The time-intensive set-up process undesirably increases the cost of lost wax casted parts. It is thus desired in the art to provide an adjustment plate that holds the fixture plate to the grinder table and allows the set-up man to adjust the position of the fixture plate with respect to the grinder surface without employing the shims of the past.